In Espoo, invasive species cleared from over 118 530 square meters with a mobile game

9.10.2025 5.39Updated: 9.10.2025 6.27

Pink Himalayan balsam blossoms. Forest in the background. — This summer, Himalayan balsam was removed in Espoo with the help of Crowdsorsa across an area of approximately 72,000 m². That’s a multiple of the amount compared to last year.Photo: Aino Peltola

Summer’s invasive species campaign has been concluded in Espoo – and the results speak for themselves. During the summer, Crowdsorsa players repelled more than 118 530 square meters of harmful lupins and Himalayan balsam. The most effective eradicator earned as much as 3 174 euros.

For the third consecutive year, Espoo mobilized citizens to fight invasive species with a mobile game. Through the Crowdsorsa app, 281 players mapped, removed and documented lupines and Himalayan balsam across the city – while getting paid for their work.

– One of the most encouraging outcomes was the strong participation of young people in this year’s missions. In Espoo, teenagers accounted for nearly half of all users, says Crowdsorsa’s CEO Toni Paju.

Players shared an impressive 12 000 euros in rewards – with Espoo’s top participant earning as much as 3 174 euros during the summer.

– With the help of various forms of volunteer work, we can inspire residents to take part in the important task of combating invasive species. The Crowdsorsa operating model is an excellent tool for encouraging Espoo residents of all ages to tackle this shared challenge for the benefit of biodiversity, says the city’s Service Manager Anne Mannermaa.

How the game fights invasive species

To complete tasks, players recorded videos of invasive species sightings before and after removal. The videos were then uploaded through the app for quality review and approval.

Each approved sighting appeared in real time on the app’s local game map. The same sites could be tackled again once at least two weeks had passed since the previous removal. This ensured that the eradication of plants was as effective and long-lasting as possible.

Part of a wider battle against invasive species

Espoo’s invasive species mission was part of a broader international effort, where Crowdsorsa was used to fight invasives in more than 70 municipalities and cities across Finland, Sweden, and Canada.

This summer alone, over 2,5 million square meters were repelled, with participants earning more than 170 000 euros in rewards.

For more information:

Anne Mannermaa
Service Manager, City of Espoo
+358 50 5285928
anne.m.mannermaa@espoo.fi

Toni Paju
CEO, Crowdsorsa
+358 40 6610072
toni.paju@crowdsorsa.com